Field of the Invention
The present invention is directed to an instrument and method for determining and displaying the appropriate angle setting for a power miter saw for cutting miter ends and miter joints.
Most power miter saws sold today are fitted with miter saw gauges which display the angle of the miter cut. However, the markings and graduations on such miter saw gauges are often counterintuitive and very confusing for less experienced users and even for professional users. Finish carpenters, in particular, when installing crown molding or trim in a room, must make numerous double mitered joints where the walls meet at an angle. The miter angle is half of the angle of the required turn. For example, if molding must make a right angle, i.e., a 90° turn, each of the adjacent pieces is cut to a 45° angle where they are to be joined.
In practice, walls often meet at angles which are not perfectly 90°. For these situations, a popular current method for calculating the miter saw setting for the double miter cut involves the following steps:
a) Transferring (“picking up”) the actual angle between the two adjoining walls to a Sliding T-Bevel;
b) Laying the Sliding T-Bevel on top of a protractor, so as to measure the actual angle;
c) Subtracting the measured angle from 180°, then dividing the subtraction result by 2, to obtain the setting needed for the miter saw angle gauge.
For single miter cuts (such as the angled end cut required for the stair spindles), the calculation would be:
a) From the acute position of the spindle: miter saw setting=90° minus the measured angle;
b) From the obtuse position of the spindle: miter saw setting=the measured angle minus 90°.
The counterintuitive calculations described above are necessary because the value of the measured angle is different from the miter angle setting to be used on a miter saw. These calculations are challenging to even experienced craftsmen, often pushing users to resort to a process of trial and error in order to obtain the proper angle setting needed for the miter saw. Specialized digital angle measuring and calculating devices (to facilitate setting the proper miter saw angle for such miter cuts) are commercially available, however they are quite expensive.
There is an unmet need in the market for a simple and inexpensive device that could translate the actual angle between two adjoining walls (as picked up by a Sliding T-Bevel) directly into the proper angle setting for a power miter saw, without the need for calculations. It would also be very desirable for such a device to be useable for single miter cuts as well as for double miter joint cuts.
Related Art
U.S. Pat. No. 4,394,801 to Thibodeaux discloses a construction tool that is used to measure the relative angle between two lines or surfaces or between horizontal or vertical and such a line or surface. It also indicates roof pitch on a separate scale. Bubble type levels are included to orient the construction tool with respect to horizontal or vertical.
U.S. Pat. No. 4,562,649 to Ciavarella discloses an adjustable carpenter's square for use determining the relative angle between two lines or surfaces. The absolute angle between the two lines is indicated, and is viewed through opening 31.
U.S. Pat. No. 4,745,689 to Hiltz discloses a measuring and layout tool that has a plurality of levels therein and indicates the relative angle between two lines or surfaces.
U.S. Pat. No. 4,144,650 to Rawlings et al. discloses a multifunction level that again shows the relative angle between two lines or surfaces. This level can be locked at a particular angle, if desired, with the locking mechanism accessible from either side of the level, thus making it easier to use.
U.S. Pat. No. 2,735,185 to Naphtal discloses a protractor that is used to measure angles between two lines or surfaces. The angle of the protractor is lockable thereby also allowing it to be usable to recreate the angle in order to draw it accurately on paper or wherever. The angle is viewed through a magnifying bubble located above the scale.
U.S. Pat. No. 1,655,887 to Bailey discloses a protractor that may be used to very accurately measure angles between two lines or surfaces or to very accurately measure very small angles, and works in the following manner. As the blades 5 and 6 are moved angularly with respect to one another, gear teeth 9, which are part of ring 7 that is in turn attached to blade 5, cause the free turning gear 11 to rotate. Gear 11 is part of the plate 10 that is attached to blade 6. Gear 11 meshes with gear 12 and causes it to turn. Rigidly attached to gear 12 is plate 13. Plate 13 is caused to be angularly displaced at a much greater rate then the two blades 5 and 6 are separated at. This is because the ratio of the gear teeth on gears 9, 11 and 12 cause gear 12 to move at an angular speed that is greater than gear 9.
U.S. Pat. No. 1,585,563 to Schlattau discloses a combination measuring instrument that measures the relative angle between two lines or surfaces, and provides a linear measuring scale, a means for measuring the outside diameter of an object, and also a scale that is used to measure the diameter of a bolt or a piece of wire. The scale for measuring a bolt or a piece of wire is an enlarged scale.
U.S. Pat. No. 1,550,755 to Steinle discloses an angulometer that is used to measure the relative angle between two lines or surfaces, including a magnifying lens to allow a very fine angular scale to be read easily.
U.S. Pat. No. 4,733,477 to Fincham et al. discloses a chalk line framing square that provides a device that is designed to aid in placing right angle intersecting chalk lines upon a floor so that tiles can be properly installed on the floor. It includes two arms that pivot with respect to one another and an angular scale that indicates the angle between the two arms.